I'm curious. What are the chances of a Hodel being cast taller than Tzietel? I don't believe I would be cast as Tzietel, and I am 5' 10". It is a school production, so I am guessing that I would be type casted as the mother (Past roles: Alma Hix (Pick-a-little) in Music Man and Mrs. Gloop in Willy Wanka). I would be fine with this, but I don't believe that this character has much of a singing role, and I am a lyric soprano who would love to have more of a singing role.

Are there any reflections/thoughts?

Just because Norma Crane sings the role in the understated style of the whole movie, don't think the stage Golde is the same! Golde needs to be a very strong singer. Sabbath Prayer and Sunrise, Sunset are both iconic and haunting, and Do You Love Me is tricky. The woman who played her in my production easily had the most powerful, gorgeous female voice in the cast. You definitely wouldn't be underused as a singer if you're cast as Golde, and really it's the best female role in the show.

Why not ask your teacher/director whether he is set on the stairstep convention? I'm sure he would appreciate knowing that you researched and planned enough that a conceptual question came up. It shows him that you're a mature and serious actress who knows what she's doing (though he probably already knows this!). And just think of how much better you can focus your energy just by finding out if you'll be seriously considered as Hodel or not.

I don't see Hodel being taller than Tzeitel as a major issue. I mean, obviously Hodel does not need to look a ton older than Tzeitel (if Hodel looked to be in her mid-twenties while Tzeitel looked like a teenager it would be an issue), but the two girls are pretty close in age, and it's not unusual for a younger sister to be taller than her older sister. (My sister is two years younger and about two inches taller than me, and no one finds it odd.) I've never known Fiddler to be a show that commonly stairsteps the siblings a la Von Trapps, so unless a director states that that is his intention I wouldn't assume that to the point of ruling out a role entirely.

Especially in school productions, I'd think they'd go with the talent available, regardless of how tall (or short) that talent is.